Australian Hewitt – seeded fourth this year – sat out the first round with a bye, as did Chile’s Fernando Gonzalez, the top seed, number two Jon Isner of the United States and his compatriot and third seed Sam Querrey.

The 2002 Wimbledon and 2001 US Open champion will have to wait until the night session at River Oaks before facing lucky loser Dewarman, who was promoted to the main draw following the withdrawal of American Mardy Fish with a lower back injury.

Fish was not the only American casualty in Houston as eighth seed Michael Russell withdrew with an ankle injury ahead of his first round match against Kazakhstan’s Mikhail Kukushkin.

And both Taylor Dent and Rajeev Ram were forced to retire hurt from their matches, Dent with a groin problem having lost his first set 6-3 against sixth seed Horacio Zeballos of Argentina and Ram at 6-2 3-0 down against Juan Ignacio Chela of Argentina.

Kukushkin instead faced another American, lucky loser Michael Yani, and advanced with a 6-1 7-5 victory.

There was some cheer for the home crowd as qualifier Ryan Sweeting eliminated Kukushkin’s countryman and fifth seed Evgeny Korolev 6-3 4-6 6-2.

In the day’s other singles matches, seventh seed Eduardo Schwank of Argentina ousted Brazil’s Marcos Daniel 6-3 6-2, Chile’s Nicolas Massu beat German Mischa Zverev 6-4 6-2, South Africa’s Kevin Anderson knocked out American wild card Donald Young 7-5 6-3 and Xavier Malisse of Belgium won 6-3 7-5 over Australian qualifier Nick Lindahl.

The United States’ doubles top seeds Bob Bryan and Mike Bryan ended Britain’s Ross Hutchins’ hopes as he and Australia’s Jordan Kerr were beaten 6-4 7-6 (7-4).